An Evaluation of the Stability of Mould Flux Properties in the Process of Continuous Steel Casting

Abstract

This paper presents research on the mould slag formed on the basis of two mould fluxes. In the conducted industrial experiments, slag was sampled in equal time intervals between adding subsequent portions of mould flux. The research focused on the an evaluation of the stability of slag parameters by assessing the change in its liquidus temperature. It was shown that a mould flux needs to be assessed individually taking into account the casting process parameters and the steel cast grade.

Experimental determination of the shell thickness within the primary cooling zone in the continuous casting process

“…The radiation coefficient of heat transfer was calculated from the Stefan–Boltzmann law between two flat surfaces: the mould flux and the mould [13]: where ϵ z is the system emissivity coefficient; T 2 is the mould flux surface temperature, K; T k is the mould inner/wall surface temperature, K. The temperature T 2 has been established in line with the condition of equality of heat fluxes [10]. The thermal resistance related to conduction is: The width of the gaseous gap was determined on the basis of the cast strand shrinkage caused by cooling in the mould and the mould wall taper, which is different for the wide and narrow wall.…”

“…It results in a different size of the gaseous gap and different conditions of heat transfer in the mould. Thermal expansion coefficient for the ETZ steel is presented in a graph (Figure 7) [13]. In the first step, the dimensional change caused by the steel shrinkage caused by cooling was determined.…”

“…Heat flux in present computing was defined as the heat transfer coefficient h , as the third-type boundary condition. The faces of the 3D model with the applied finite element mesh, for which the HTC should be computed, were divided into three groups: The mould outer – so-called water side: h = 18,000 W m −2 K −1 [8,13]. The contact of the solidifying strand surface with the inner side of the mould – the model presented in the ‘Modification of the boundary condition in the primary cooling zone’ section. The liquid steel meniscus surface–temperature measured in the tundish t = 1515°C. …”

The analysis of gas evolved from casting powder during heating in the mold

“…The main reason to apply casting powder is to facilitate the extraction of the pre-solidified strand from the mold to the secondary cooling zone. The proper implementation of other important functions, such as lubrication, thermal insulation of liquid steel, refining of non-metallic inclusions, or heat extraction between the strand and the mold, depends on the stability of thermophysical properties that are controlled by the chemical composition [1][2][3].…”